It was my pleasure Jim K. I decided to stop lurking and contribute to the discussion.

When I started researching early breach loaders it was surprising to find out how far back they go. According to the Oxford Companion to Military History, Leonardo da Vinci illustrated a hackbutt (a type of early, heavy matchlock musket) with an unscrewing, or ‘turn-off’ breech in his Codex Atlanticus of c.1500-10.